Common nowadays in Web browsing and interaction is the use of embeddable units such as display advertisements and widgets. Preferably one would like to perform live updates for an embeddable unit to make information display and advertising more dynamic and relevant. Three requirements in solutions are key to the success of these live updates.    1. High scale: Such a solution would be equally effective regardless of whether the embeddable unit exists on only a few web pages, or on thousands of pages.    2. Low cost: Such a solution would have low server processing and bandwidth requirements as compared to other live update solutions, making it cheaper to implement.    3. Fast and reliable change propagation: Such a solution would result in changes propagating to all embed sites and clients as soon as the embeddable unit is updated on the provider's side.
An advertisement or widget may appear on many web pages, so the ability to update these units without having to replace the embed tags each time, and in a manner that is fast, reliable, scalable, and cost-efficient, is very valuable to customers, including advertisers, publishers, and widget creators. The present invention addresses these requirements for live updates and advances the art by providing techniques to accomplishes all three goals at once: scalability, low cost, and fast, reliable changes.